Sprague-Dawley rats are uninephrectomized and are then immunized with a sheep antibody directed against brush border antigen. This results in a membranous glomerulonephritis. This study is designed to study how glomerular sclerosis progresses. Immunofluorescence studies allow us to study the topography and composition of extracellular matrix. Preliminary studies show that immune deposits disappear within 36 weeks whereas, glomerular sclerosis progresses. Extracellular material appears to contain collagen type IV.